Physicists Investigate Possibility of an 'Unhiggs'

This figure represents a five-dimensional diagram relevant to how the Unhiggs affects certain parameters in particle physics models. Physicists are calculating the properties of the Unhiggs so that it will be recognized at the LHC, if it exists. Image credit: Falkowski and Pérez-Victoria.

(PhysOrg.com) -- One of the biggest goals of the LHC is to discover the Higgs boson, the only particle in the Standard Model that has not yet been observed. In general, physicists are pretty confident that the Higgs does in fact exist, although they have spent a lot of effort searching for the particle in less powerful accelerators without success. While patiently waiting for the LHC to reach its full energy and a Higgs particle to leave a signature in a detector, some physicists are investigating alternative scenarios. One of the most recent proposals is that the Higgs is not a particle, but an unparticle called the Unhiggs.

The Unhiggs idea was first suggested in a paper published in November 2009 by physicists David Stancato and John Terning of the University of California, Davis. The Unhiggs is not all that different from the Higgs, except that it demonstrates unparticle behavior and, subsequently, does not fit in with the Standard Model. While a particle has discrete parameters, the Unhiggs’ parameters are continuous. In this sense, the Unhiggs is itself a continuum, and can be thought of as a collection of many Higgs bosons, each carrying a fraction of the Unhigg’s total value.

“In particle physics, we are used to dealing with (surprise) particles,” Adam Falkowski, a physicist at Rutgers University, told PhysOrg.com. Falkowski and Manuel Pérez-Victoria of the University of Granada are also investigating the possibility of the Unhiggs. “One property of particles is a well defined mass. For an unstable particle (such as the Higgs boson in the Standard Model), we can experimentally determine the mass by measuring the momenta of its decay products and computing the so-called invariant mass. Particles show as bumps, or resonances, in the invariant mass spectrum or other kinematical distributions.

“Unparticles, on the other hand, do not have a well defined mass; in fact, an unparticle can be thought of as a superposition of an infinite number of particles with different masses. For this reason, unparticles don’t show up as resonances. Instead, they show up as subtle modifications of kinematical distributions measured by experiment, and therefore they can be difficult to spot.”

In their study, Stancato and Terning showed that the possibility of an Unhiggs is theoretically consistent (which was not obvious a priori). The physicists found that the Unhiggs can do many things that the Higgs does. For example, both the particle and the continuum possess a non-zero vacuum expectation value, which can “break electroweak symmetry” and “unitarize WW scattering” - abilities that are important for giving other particles mass, which is a fundamental role of the Higgs. In addition, the scientists found that the Unhiggs can do something that the Higgs cannot: provide a solution to the so-called little hierarchy problem.

More recently, Falkowski and Pérez-Victoria have further investigated the properties of the Unhiggs. In their study, they have explored certain experimental predictions of the Unhiggs proposal, such as how the Unhiggs affects precision observables measured by experiment. The scientists found that the Unhiggs is even more like the Higgs than previously thought, in that it closely mimics the Higgs for some light masses. They also found that the primary difference between the Unhiggs and the Higgs is due to their different propagators: while the Higgs’ propagator is mathematically described as a pole, the Unhiggs’ propagator is a branch. This characteristic is what makes the Unhiggs difficult to detect in collider experiments.

“Propagators are mathematical functions that are used for computing amplitudes in quantum theories,” Falkowski explained. “Amplitudes determine the probability of certain events to occur in our colliders. The ‘pole’ means that the propagator becomes very large for certain values of the momenta corresponding to the particle mass; mathematically, this is the origin of resonances in kinematical distributions measured by experiment. Propagators for unparticles do not have poles, but rather branch cuts (discontinuities of the imaginary part), and therefore unparticles do not show up as resonances.”

Instead, when the Unhiggs “decays,” it becomes suppressed, making its decay product mostly invisible. Still, the physicists say that a more detailed analysis of the collider’s constraints is necessary in order to determine if the Unhiggs might be observed. If physicists do find a way to determine its existence, the Unhiggs could possibly reveal information about the elusiveness of new physics beyond the Standard Model. Falkowski and Pérez-Victoria are currently working on a theoretical framework where not only the Higgs but also the W and Z bosons have unparticle components.

“At the present stage it's hard to say whether the idea is useful, that is to say whether it solves any problems that are troubling particle physicists,” Falkowski said. “Our approach in the paper was rather that the Unhiggs could be the reality, and explore consequences of that assumption. As I said, a priori it was far from obvious that the Unhiggs is theoretically consistent, or if it's consistent with all experimental results up to date. The usefulness of this direction of research is that it allows the experimental physicists to prepare their experiments such that the Unhiggs, if present, would not be missed.”

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47 comments

Sounds like a round about description of the ether theory. Which I think is still a better explanation than nothing. How does a particle of light know how fast it is going from one moment to the next without a frame of reference? I see no logic in explanations of the results of the Michelson - Morley experiment. I don't think dark matter exists. And don't be surprised if the LHC can't find the Higgs either. I think the LHC's greatest claim to fame might be what it DOESN'T find. Dark energy and the expansion of the universe? Ever see a drop of oil hit water? I think much of what we think we know is wrong.

Dark matter has to exist. Where does the "space" in between matter come from? Before the big bang all matter was compressed together, there was no room for entropy and thus there was no "flow of time".

The Big Bang was not only the start of the Universe as we know it, but it was also was the beginning of the space in which all matter expanded into. One could maybe theorize that it was the Space that was created and the matter just expanded into it, like a watermelon in a pressure chamber - but I digress.

My point is that the space in outer space is something and there is more and more of that something as the universe expands. I believe that something is the dark matter.

I don't know if the LHC will prove anything regarding dark matter, but I believe it exists, I don't see how it cannot. I believe that if or when we figure out the Dark Matter then we will also be able to figure out how and why the Big Bang happened.

Yes that is exactly my take on this article as well, Skeptic. They are essentially saying 'oh wait, what if the fundamental particle for gravity is not a particle but a force' and to me that seems to be the more reasonable assumption. Sounds like they are just covering their butts in case the LHC *surprise surprise* doesn't find anything. Next they will be saying 'oh wait, what if the gravity field was in fact the quantum fluctuations of the vacuum all along'. I can see where this is heading.. very much in the same direction as those proclaiming the end of the world.. they just keep refining that end date that never comes.

Crackpot - while it is true that most physicists believe that the Higgs probably exists, they base their belief on the fact that the standard model predicts it. It is certainly true that it may or may not truly exist. But this would be even more exciting than if it does, because decades of exploration at the lower energies currently available to us have simply verified that the standard model is true in those energy realms to an astonishing accuracy, and the lack of the Higgs would imply new science beyond the standard model. But as this article shows, there is no limits to the imaginations of scientists on the implications of either a lack of the Higgs, or variations that can explain mass using some other mechanism.

I also find it mind boggling that you claim that attempting to verify the predictions of theorists by direct experimentation and measurement is bad science. To me (and I suspect most scientists) this is what good science is all about.

Sounds like a round about description of the ether theory. Which I think is still a better explanation than nothing..

Yep, one of the ways, how to introduce unparticles is a concept of fractal fluctuations which appears inside of gas. For example clouds are scale invariant unparticle stuff, similar to Perlin noise. There is no effective reason for lower limit in scale of vacuum fluctuations - but I'm not sure, if we could directly observe them from geometrical reasons. They would always appear like homogeneous noise, when their size becomes too distant from human scale size.

I think some of you above are mixing up mass and gravity, aren't they separate things? The Higgs particle, or in this case the unparticle, helps assign mass to certain particles, but gravity is a force acting between particles that have mass, and which is conveyed by the virtual photon.

Whatever model, standard or Superstrings that we may have developed can not serve as the basis for looking at the unknown. We need to keep all possibilities open. Let me say that there are more than six family of quarks accepted till now, with top quark as the heaviest. Ther may well be much heavier quarks AND EVEN THE NEUTRAL VARIETY, that may well decay to lower forms so very fast under the unified field that we can hardly expect to sense them in our finite response time detectors. Such speculations by way of perspectives have been made in an article ' Mysteries of the Universe- some perspectives' available on the website of The Foundational Questions Institute of Physics & Cosmology, located in Pennsylvania, USA.

Scalar field energetically preferring nonzero values as Higg's field, doesn't have to be fundamental but could just represent behavior of some different, probably more complicated field - for example describing its local asymmetry (it's zero would denote symmetry).And generally I agree that this field doesn't have to lead to some special, well defined excitation (particle).Fluctuational modes of these fields should generally interact extremely weakly, but should theremalize through universe history with observed 2.7K background EM radiation and could be missing 'dark energy' required in cosmological models.

Even 'artificial particles' like quants of magnetic field in superconductors (fluxons) seems to behave like real (spin 1/2) particles - to which interference applies, which have momentum and so mass...http://adsabs.har...46.2381W ) ... the question is if this mass is also gravitational, what should be verified experimentally ... But generally gravitational mass is kind of curvature of local time dimension (central axis of light cone), which seems to compensate local deviations from the equilibrium, like all kind of particles (stable excitations) or 'dark energy' type fluctuations (probably thermodynamical?).

The unparticle theory is well substantiated in context of random nested density fluctuations of dense gas. UnHiggs field has its direct counterpart in foam of dark matter, which has a scale invariant character of Perlin noise as well.

Try to imagine, Universe as a whole is completely random and we are just one of fluctuations, which is interacting with another ones: both larger, both smaller ones. The more distant from our dimensional scale the another density fluctuations will be, the more fuzzy they would appear, like landscape under haze where all shapes vanish.

As the result, each colliding particle would have its own version of Higgs boson at large energies. After all, even Standard Model proponents consider many versions of Higgs particle already, because they observed a number of supersymmetric phenomena, but they found no particular Higgs boson.

In this sense, Unhiggs is an attempt to save Higgs boson concept in the eyes of both publicity, both formal models, instead.

In more illustrative version, Unhiggs field is analogous to coat of virtual quarks, in which all elementary particles are surrounded at small distances. This coat glues particles together at smallest distances. It's responsible for so called Yukawa coupling, responsible for pairing and gluing of nucleons and quarks inside of atom nuclei, for formation of top-quark pairs, glueballs, pentaquark and another artifacts, which were observed recently at Tevatron.

But such field exists at all scales and it manifests by Casimir force mediated by virtual photons at micrometer scale, or dark matter at megaparsec scale, for example. It means, this field has a scale invariant character of fuzzy unparticles, which are changing their size accordingly to carrier particles.

The most problematic part of Unhiggs detection at LHC is the strangelet concept instead: it could enable formation of clusters of particles, analogous to stable microscopic black holes of Randall-Sundrum model.

Something living e.g. 10^-25s as (virtual) interaction bosons are rather some metastable states observed only as a resonance - it's difficult to call them particles. And similar about (un)Higgs ... it could be so wide that it would be practically unobservable ...The real particles should be much more stable, hold together by its quantum numbers and probably topological properties of surrounding fieldhttp://demonstrat...arities/

About Casimir force - the nonzero ground state energy can be imagined as just the energy of the potential well itself.

Such unstable particles can still be observed by their collective effects, for example by jet suppression during particle collisions. Just because it's difficult to call them particles they're called an unparticles.

I think unhiggs field is the notion that it Higgs doesn't couple wavemodes/forces into a particle with real mass, but strongly couples these wavemodes to themselves, so that they are shielded from the random fluctuations in the vacume and hence the system as a whole can sit idle as a standing wave in space. It takes significant energy of specific tunes to disturb this wavepattern. The level of resistance against "detuning" makes it hard to move the system through space, wich we like to call inertia/mass. Photons on the other hand can't keep still, and are said to have zero restmass. This particle / wave duality and zero mass has bugged me long time, what if we assume a photon, like a particle is a coupled system of mutual interacting waves, but without the (un)higgs field to shield it from interacting with even random fluctuations in the vacume. In that case it would be kicked around by it, hence travel, but appart from redshift losses, wich hints that the vacume really does interact

, most photonic waves are of sufficient electromagnetic coupling/coherence to ensure that they will not disperse, but travel in a certain direction as a single photon. Dark energy and gravity I regard as photonic energy with even weaker coupled than lightphotons, to resist being kicked around by random vacume fluctuations and therefor disperse in all directions manifesting themselves as omnidirectional forces. I would think gravity photon is shaped as a subtractive wave, that interacts and donates its energy to the vacume fluctuation waves, thus making this space denser, but at the expense that gravity experience severe "redshift" loss (or should i say aetherfriction) and diminishes quickly with distance while darkenergy would be additive shaped waves, that pick up some energy from vacume waves, allowing these waves to relax, lowering the spatial and energydensities of the vacume and implies that darkenergy grows with distance.

It could well be that the darkenergy wave is shaped such that it will only leech from certain frequencies of vacume flux waves. As waves at these frequencies get depleted, darkenergy might fail to scavenge the rest of the vacume flux and space might become transparant for its effects well before a Big Rip. Studies indicate that the expansion of space in the long past was not a continuous linear increasing process, but sometimes slower, sometimes faster, making this an entertaining possibillity. Darkenergy waves themselves might not only gain in strength, but also gradually change shape through interaction with the vacume and morph into something different over times. Likewise gravity waves could perhaps evolve into a stronger / weaker dorce or another force, depending on changes in overall vacume energydensity or changes vacume energy in certain frequenciebands.

Dark matter has to exist. Where does the "space" in between matter come from? Before the big bang all matter was compressed together, there was no room for entropy and thus there was no "flow of time".

The Big Bang was not only the start of the Universe as we know it, but it was also was the beginning of the space in which all matter expanded into. One could maybe theorize that it was the Space that was created and the matter just expanded into it, like a watermelon in a pressure chamber - but I digress.

My point is that the space in outer space is something and there is more and more of that something as the universe expands. I believe that something is the dark matter.regarding dark matter, but I believe it exists, I don't see how it cannot. I believe that if or when we figure out the Dark Matter then we will also be able to figure out how and why the Big Bang happened.

Dark matter also does not have to exist because we are inferring its existence from observed discontinuities from current theory. It is almost as likely to me that current theory is wrong or incomplete. I guess I hope that's true because it is more interesting.

The combination of trivial and topological band insulators within topological insulators and superconductors is bringing anyons and plektons — unparticles that behave neither according to purely Bose nor Fermi statistics.

My main concern regarding this article is that someone is going to latch onto it and say that the unHiggs is the Anti-Higgs and the LHC is going to become the newest weight(ok, mass)-loss fad in the media.

Of course, from layman or even common physicist perspective the fact, Higgs is unparticle effectively means, no distinct Higgs particle signal will be ever found (we should prepare special "pure" collider jets, composed of unique particles to demonstrate it).

The signs, physicists aren't so sure by Higgs concept at all appeared already in media between lines - the question is, whether physicists could admit openly before publicity, LHC is useless with respect to search of Higgs boson even by their own theories - if they wasted so much money in it.

After all, dual situation appeared recently in media, when scientists started to speculate, (primordial) gravitational waves cannot be found at all due the "quantum-spread", which renders detectors of gravitational waves useless.

Such situation isn't accidental at all with respect to AdS/CFT duality: the success or problems with particle search at Planck scale will be replicated/mirrored at cosmological scales and vice-versa. The same problem we can expect with so called WIMPs detection.

should be interpreted like: "Uhm, well, ... we really don't believe, Higgs boson will be ever found at LHC - so we should concentrate to supersymmetry, for not being blamed completely before publicity".

This is basically demo, how seemingly spontaneous scientific PR is working. The similar U-turn we could expect later regarding estimations of collider safety.

Wouldn't that make the Universe contract? (That would be assuming Dark Matter is in part responsible for the expansion of the Universe)

I'm sorry, but saying Dark Matter can annihilate itself doesn't really make sense. How/why do you think it can? I'm not trying to argue, just trying to understand your point. Granted we don't even know what it is yet, but just the idea of something self destructing without outside influence, it would happen the moment it came into existence. I wouldn't think that something would be able to assert much influence on the rest of the Universe if it annihilated instantly.

fourthrocker-expansion of the universe is an easily seen fact......as far as dark matter...space itself could technically be predominantly dark matter...we havent gotten far enough to find out....

I have no problem with expansion of the universe, it's pretty obvious since almost every galaxy is moving away from us. My problem with dark matter is that it's existence is inferred, it hasn't been seend or proven to exist or fit in current theory. The hallmarks of something that doesn't really exist, like bigfoot. Until someone actually has it to show me, it is more likely to not exist.

For me it's rather surprising, millions - or possibly billions - of well educated people thinked about light spreading through space and it seems, they never considered simplest possible model of it: the ripples at water surface.

Due their dispersion, the speed of ripples decreases gradually, which could be interpreted like omnipresent expansion of space-time with distance. After then we could put a question, how such expansion would appear from outside? The light would appear frozen in gradually expanding space around sources in similar way, like if they would surrounded by sparse cloud of invisible matter. As the dispersive environment in vacuum could serve well known cosmic microwave noise.

I'm not saying, this model is ultimate description of vacuum - but why we shouldn't consider it, if we haven't more illustrative explanation in this moment anyway - and think a bit about its consequences? I presume, people are extrapolating a much more difficult ideas in their common lives.

This simple model connects both omnidirectional expansion of space/time, both dark matter by simple relation: seeming deceleration caused by presence of dark matter will be equal to product of Hubble constant and speed of light. The same deceleration can be observed at the case of so called Pioneer anomaly with some 10% error.

We can extrapolate this idea further and we could ask, whether all forces including gravity aren't of dispersive nature. Recent connection of gravity to entropy revealed by Erik Verlinde indicates, this idea can be substantiated. It means, if dark matter or expansion of space is dispersive effect, then every gradient of matter will be a result of energy dispersion as well and we could consider particles, planets and galaxies as a giant nested droplets of dispersive environment.

Concerning dark matter annihilation, it would be a more natural to consider, dark matter itself is formed by antimatter - we shouldn't forget, we still have large amount of antimatter missing from "Big Bang". This explains observation of gamma radiation characteristic for annihilation at the proximity of Earth or center of Milky Way at places, where antimatter could get into contact with ordinary matter. We can consider, during inflation hot mixture of antimatter and matter was in intimate contact. But the further development was completely different: antimatter travels against arrow of time, which means, it expands, where matter collapses and vice-versa and inflation separated both components from each other.

This strategy in thinking is simple and it follows Occam's razor: we should always use the simplest explanation possible. And the explanation, which solves more problems in the single moment should be considered first. Especially at the moment, nobody has considered it so far.

matter does not exist. Of course, if you call energy "matter", then it does, but it only exists in that shape. What we call matter, is energy organization structured. We should focus on that, not on finding "matter". Surprise scientists have not learned since the classic theory of physics found its limitations.

What is God Particle? According my fresh thought:1. It is a naked singularity of mass or the smallest black hole in the Universe; 2. It has huge naked mass, gravitation and inertia;3. It is not a material particle;4. It is not in the Standard Model of elementary particles;5. It is an Ultimate Particle, cannot be decay;6. Its Mass cannot be converted into energy; 7. The lowest limit of its mass is about 10.9&#956;g, and the upper limit is about 0.67*10^6kg, that means that its mass may be exceeded one kilogram! 8. Estimated mass of Higgs Particle is about 16 orders of magnitude smaller than lower limit of Mass of God Particle at least. So the mass of God Particle is substantially undervalued by mainstream physics9. So Higgs particle is not God particle;10. And so I believe that to find the God particle with LHC is an impossible mission, LHC efforts will be ended in failure, and it is destined. I think that to find God Particle with colliders (such as LHC) is an extremely extravaga

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